This invention is particularly adapted for use with heat exchanger assemblies of the type having a heat transfer core element which includes a plurality of fins in parallel stacked relationship for defining heat transfer surfaces and a plurality of fluid carrying tubes extending transversely through the fins for defining a fluid circuit. Heat exchanger assemblies of this type are commonly employed in the automotive industry as oil coolers, air heaters, and air conditioning system condensers.
In all such heat exchanger assemblies it is necessary to connect various tubes together to complete the assembly. In order to form the connections between two tubes it is conventional practice to use a bell and spigot type joint which is fluxed and soldered. In other words, the end of one tube is expanded to increase its internal diameter so that it is capable of receiving the end of the other tube which is to be connected to it. Thereafter, the tubes are permanently connected by a soldering operation which normally includes the use of a fluxing material to insure good bonding and a pressure tight seal.
Such tube joints require a significant amount of heat since the tube joint must be heated to a sufficient temperature to melt the solder material. Additionally, radiator assemblies including soldered joints are normally steam cleaned to remove flux material which may have flowed into the interior of the tubes. A solderless joint, on the other hand, does not require heat for forming a connection between tubes and the resulting assembly normally does not require steam cleaning. Hence, a significant energy saving can be achieved.
It is also significant to note that the source of heat for soldering heat exchanger assemblies is normally natural gas. In recent years, the supply of natural gas has been reduced drastically for manufacturing facilities in certain parts of the country. Manufacturing facilities whose operations are highly dependent on a large and continuous supply of natural gas can be shut down in the event of a shortage. Therefore, the elimination of soldered joints in heat exchanger assemblies is attractive since it eliminates a portion of the dependency on natural gas in the manufacturing operation.